Spatiotemporal dynamics of triglyceride storage in unilocular adipocytes.
Bottom Line: Exogenously added free fatty acids are rapidly adsorbed by mLDs and concurrently get esterified to TG.This process is greatly accelerated by insulin. mLDs transfer their content to the cLD, serving as intermediates that mediate packaging of newly synthesized TG in the large interior of a unilocular adipocyte.This study reveals novel cell biological features that may contribute to the mechanism of adipocyte hypertrophy.
Affiliation: Division of Endocrinology, Diabetes, and Clinical Nutrition, Department of Medicine, Portland, OR 97239.Show MeSH
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Mentions: We further examined the ultrastructural organization of mLDs in unilocular adipocytes using electron microscopy. Electron-lucent mLDs ranging up to 1 μm in diameter were frequently observed in adipocyte cytoplasm in the vicinity of or attached to the cLD (Figure 3A). mLDs were surrounded by or associated with mitochondria (Figure 3, A–C). Tubular membranes of the smooth ER decorated with budding vesicles were frequently observed in the areas containing mLDs and mitochondria (Figure 3, B–D, arrowheads). Furthermore, some mLDs were decorated by electron-lucent vesicular material, which may represent the ER or precursors of mLDs (Figure 3E). Of interest, rough ER membranes were not typically associated with mLDs (Figure 3F).
Affiliation: Division of Endocrinology, Diabetes, and Clinical Nutrition, Department of Medicine, Portland, OR 97239.